Elastase Producing Strains And Fermentation Conditions Of A Preliminary Study

Elastase is a kind of protease that can specially degrade elastin , so it has broad applications in medical therapy, food processing , daily use chemicals industry and so on. In this study, elastase-producing strains were screened and isolated from a special environment, and we obtained 1 strain from 363 elastase-producing strains by efficient screening method. This strain has stable capability of producing elastase with higher enzyme activity, we studied its morphologic character, physical and biochemical characteristics . And it was identified as Bacillus sp. EA9. Elastase productivity of Bacillus mutant EA9314 was improved 33% higher than that of initial strain EA9 after mutated by ion implantation and ultraviolet. The fermentation condition of strain EA9314 was studied. Glucose and yeast extract were better carbon and nitrogen source, respectively. K₂HPO₄ and MgSO₄ were the appropriate inorganic salts. Soybean flour can greatly improve elastase productivity. The ANOVA results from Plackett-Burman experiment demonstrating the effect of four factors on elastase production was yeast extract >glucose> MgSO₄ > K₂HPO₄ . The orthogonal design was adopted to optimize the concentrations of glucose and yeast extract. In a word,the optimal medium was consisted of 2% glucose, 1.5% yeast extract, 0.1% soybean flour, 0.1% K_HPO₄ , 0.01%MgSO₄ ; The optimal culture conditions were as follow: initial pH 6.5-7.0, medium cubage 20ml/250ml, inoculum size 6%. In optimum condition , it had the highest elastase production.